RESUMEN
The exposure assessment component of a Wildlife Ecological Risk Assessment aims to estimate the magnitude, frequency, and duration of exposure to a chemical or environmental contaminant, along with characteristics of the exposed population. This can be challenging in wildlife as there is often high uncertainty and error caused by broad-based, interspecific extrapolation and assumptions often because of a lack of data. Both the US Environmental Protection Agency (USEPA) and European Food Safety Authority (EFSA) have broadly directed exposure assessments to include estimates of the quantity (dose or concentration), frequency, and duration of exposure to a contaminant of interest while considering "all relevant factors." This ambiguity in the inclusion or exclusion of specific factors (e.g., individual and species-specific biology, diet, or proportion time in treated or contaminated area) can significantly influence the overall risk characterization. In this review, we identify four discrete categories of complexity that should be considered in an exposure assessment-chemical, environmental, organismal, and ecological. These may require more data, but a degree of inclusion at all stages of the risk assessment is critical to moving beyond screening-level methods that have a high degree of uncertainty and suffer from conservatism and a lack of realism. We demonstrate that there are many existing and emerging scientific tools and cross-cutting solutions for tackling exposure complexity. To foster greater application of these methods in wildlife exposure assessments, we present a new framework for risk assessors to construct an "exposure matrix." Using three case studies, we illustrate how the matrix can better inform, integrate, and more transparently communicate the important elements of complexity and realism in exposure assessments for wildlife. Modernizing wildlife exposure assessments is long overdue and will require improved collaboration, data sharing, application of standardized exposure scenarios, better communication of assumptions and uncertainty, and postregulatory tracking. Integr Environ Assess Manag 2024;20:674-698. © 2023 SETAC.
RESUMEN
The benefits people obtain from ecosystems vary from direct benefits that are easily monetized (e.g., timber) to indirect benefits that are not easily monetized (e.g., maintenance of water quality). Commonly, there is wide variation among individuals in the values placed on ecosystem benefits or services. The lack of consensus both in identifying ecosystem services and in valuing them with respect to other services poses a great challenge to those charged with evaluating changes in the provision of ecosystem service after, for example, a natural disaster. Natural resource economics provides some tools, but economics alone will not ensure a balanced, holistic assessment. An inherent complexity in valuing services is often associated with the interrelationships between services and the background and expertise of those leading the assessment. We argue that a holistic evaluation of ecosystems founded on solid expertise in ecosystem dynamics is essential for the accurate assessment of ecosystem services. A reductionist approach to ecosystem service valuation often fails to capture ecological dynamics that are vital to the functioning and ultimate provision of services. In this article, we present case studies of ecosystem services valuation for forest fires, dam removal, and chemical contamination of sediment to explore the complexity of ecosystem service valuation. Additionally, we offer assessment strategies for recognizing the importance of holistic assessment of ecosystem services.
